OBJECTIVE: This study aimed to determine the accuracy of computed tomographic (CT) localization and CT-based diagnosis of sentinel lymph nodes (SLNs) metastasis. METHODS: Thirty-four patients with confirmed breast cancer underwent 40-row CT scanning, and the first one or several lymph node(s) in the lymphatic drainage pathway was/were defined as the SLN(s). Dye and γ probe-guided SLN biopsy was performed on all patients. To accurately localize the SLN, 19 patients (55.9%) underwent the percutaneous lymph node puncture procedure. The morphologic features of all the SLNs on CT scans were analyzed and compared with the SLN biopsy pathologic diagnosis. RESULTS: Sentinel lymph nodes were successfully identified for all patients without any significant adverse effects. All localized SLNs corresponded well with SLNs identified on SLN biopsy, with an accuracy of 89.5%. Accuracy increased to 100% when the CT scan technique was combined with the blue dye method. The size criteria for metastatic diagnosis had a sensitivity of 85%, which increased to 94.7% when long-to-short-axis ratio and margin characteristics were also considered. CONCLUSIONS: The CT lymphography combined with the blue dye method accurately localized the SLNs. The CT-based diagnostic criteria improved the diagnostic accuracy of SLN metastases and were useful for evaluating the axillary status in early stage breast cancer patients.